What is this answer? A blank is a combination of two or more substances, elements, compounds, or both, in the same place but not chemically combined

A10nc charge sits at a point in space where the magnitude of the electric field is 1500 n/c. what will the magnitude of the field be if the 10 nc charge is replaced by a 20 nc charge? assume the system is big enough to consider the charges as small test charges.